NASA is advancing Space Reactor-1 Freedom, a nuclear electric propulsion demonstrator for Mars scheduled to launch in December 2028. The agency wants significant design work completed by June 2026, with assembly, integration and testing running from January to October 2028 before launch.
The mission pairs a more than 20 kW fission reactor fueled by HALEU and uranium dioxide with the Power and Propulsion Element previously built for the Lunar Gateway. The reactor is expected to switch on within 48 hours after launch and use xenon-fed electric thrusters for a transit of roughly one year to Mars.
NASA presents SR-1 Freedom as a pathfinder for future, higher-power nuclear missions, including lunar surface power and later Mars operations. The agency is also using recent high-power electric propulsion testing, including a 120 kW lithium vapor thruster trial at JPL, to mature the broader technology base for deep-space nuclear architectures.